Image forming apparatuses are well-known, which are operated by an electro-photographic method, and incorporate an exposure section to form latent images on a photoconductive surface, by a lens array including an aligned cylindrical lens, and said lens array focuses light rays emitted from a light source including aligned plural light emitting bodies, such as LED (being a light-emitting diode) arrays.
In most cases of image forming apparatuses, in order to improve dust prevention effect, productivity, and maintenance work of the image forming apparatuses, structuring elements, such as the exposure section, the light source, the driving circuit of the light source, and the lens arrays, are united in a single unit as a print head.
Dust particles, such as toner particles flying within the image forming apparatus, tend to accumulate on a dust prevention glass surface which is mounted on the end or in front of the end of the lens array which works as a light emitting surface of the exposure section (included in the print head). The accumulated dust particles tend to generate line defects on any image formed by the image forming apparatus.
In order to prevent generation of said line defects, well-known is an image forming apparatus which incorporates a cleaning means (See Unexamined Japanese Patent application Publication 2007-72,321). Said cleaning means has a cleaning pad as a cleaning member, the cleaning pad is configured to come into contact with the light emitting surface of the print head, and to move on a guide groove provided on the side of the print head.
Further, disclosed is an image forming apparatus having another cleaning means (See Unexamined Japanese Patent application Publication 2004-17,607). That is, a dust prevention glass surface is provided on the light emitting surface of an optical unit structured to emit the light rays upward. While a cleaning pad or a cleaning brush is in contact with said dust prevention glass surface from the top, said dust prevention glass is driven so that the dust particles drop into a dust box provided on an appropriate position of the outside of the light emitting surface.
However, in a case of an image forming apparatus having a light emitting surface of the exposure section (being the print head), in which said light emitting surface faces downward, the above structure is not usable.
That is, any dust particles which are removed from the light emitting surface by the cleaning means, accumulate on the cleaning member which faces upward and wipes the light emitting surface, and the dust particles also accumulate on an end portion of the print head at which the cleaning member stops and all the dust particles are gathered together.
After the dust particles have accumulated on the end portion, said dust particles fall down due to vibration or on impact shock, and stain the image forming apparatus, which causes problems of defective printed images.
Specifically, concerning an image forming apparatus having an exposure section which is opened or closed by a hinge mechanism during the maintenance work, the impact shock due to opening or closing operation causes the above dust problems.